Flavour Physics in the LHC Era Lecture 2 of 2 Tim Gershon University of Warwick & CERN LNFSS 2012 11th May 2012 Tim Gershon Flavour Physics 1 Contents ● ● Yesterday – Definitions of “flavour physics” and “the LHC era” – Why is flavour physics interesting? – What do we know about it as of today? Today – What do we hope to learn from current and future heavy flavour experiments? Tim Gershon Flavour Physics 2 Summary from yesterday sin 2 ∣ md / ms∣ ∣V ub /V cb∣ Adding a few other constraints we find = 0.132±0.020 = 0.358±0.012 Consistent with Standard Model fit ● some “tensions” Still plenty of room for new physics Tim Gershon Flavour Physics 3 Topics to cover today ● Flavour physics at hadron colliders (mainly LHCb) ● More on CP violation ● – The third Unitarity Triangle angle: γ – Tree-dominated decays vs. loop-dominated decays – CP violating phase in Bs0 oscillations – CP violating phase in D0 oscillations Rare decays – ● Bs0→μμ, B→K*μμ, Bs0→φγ, K → πνν Future experiments Tim Gershon Flavour Physics 4 Flavour physics at hadron colliders Tim Gershon Flavour Physics from Val Gibson HCPSS 2009 5 Geometry ● ● – In high energy collisions, bb pairs produced predominantly in forward or backward directions LHCb is a forward spectrometer The LHCb Detector JINST 3 (2008) S08005 Tim Gershon Flavour Physics 6 LHCb detector features ● Tracking and calorimetry – – ● VELO – ● reconstruct displaced vertices RICH – ● basic essentials of any collider experiment! muon chambers particle ID (K/π separation) Trigger – fast and efficient Tim Gershon Flavour Physics 7 LHC performance 2011 Tim Gershon Flavour Physics LHCb design luminosity: 2 1032/cm2/s 8 Note “luminosity levelling” Tim Gershon Flavour Physics 9 2011 data taking 1.1/fb on tape Average #interactions/visible event (μ) ~ 1.5 c.f. design value ~ 0.4; 2010 data taking up to 2.5 March Tim Gershon Flavour Physics October Data taking efficiency close to 91 % 10 2011 data reprocessing Start October Tim Gershon Flavour Physics End November 2011 data reprocessing completed in 8 weeks 11 Heavy flavour production @ LHCb “Prompt charm production in pp collisions at √s = 7 TeV” LHCb-CONF-2010-013 “Measurement of J/ψ production in pp collisions at √s = 7 TeV” Eur. Phys. J. C 71 (2011) 1645 – "Measurement of σ(pp→bbX) at √s = 7 TeV in the forward region" Physics Letters B 694 (2010) 209 Tim Gershon Flavour Physics 12 What does ∫Ldt = 1/fb mean? ● Measured cross-section, in LHCb acceptance – σ(pp→bbX) = (75.3 ± 5.4 ± 13.0) μb ● PLB 694 (2010) 209 – So, number of bb pairs produced 1015 x 75.3 10–6 ~ 1011 ● Compare to combined data sample of e+e– “B – 9 factories” BaBar and Belle of ~ 10 BB pairs for any channel where the (trigger, reconstruction, stripping, offline) efficiency is not too small, LHCb has world's largest data sample ● – p.s.: for charm, σ(pp→ccX) = (6.10 ± 0.93) mb LHCb-CONF-2010-013 Tim Gershon Flavour Physics 13 The all important trigger Challenge is ● to efficiently select most interesting B decays ● while maintaining manageable data rates LHCb trigger scheme L0 – high pT signals in calorimeters & muon chambers Main backgrounds ● “minimum bias” inelastic pp scattering ● other charm and beauty decays HLT1 – associate L0 signals with tracks & displaced vertices HLT2 – inclusive signatures + exclusive selections using full detector information Handles ● high p signals (muons) T ● displaced vertices Write to tape Tim Gershon Flavour Physics 14 Spectroscopy ● I've talked about the headline items of flavour physics – – ● CP violation, searches for new physics what we tell the funding agencies, and the press But, much of the physics performed by flavour experiments is the study of properties of hadronic states – – lifetimes, masses, decay channels, quantum numbers and the discoveries of new ones Most highly cited papers from BaBar and Belle Tim Gershon Flavour Physics 15 – Discovery of the lightest bb state – 2008 The BaBar Collaboration Only recoil γ is reconstructed ● 2 m b 1S = 9388.9 3.1 ±2.7 MeV / c −2.3 2.3 2 m 1S−m b 1S = 71.4 −3.1 ±2.7 MeV / c B 3S b 1S = 4.8±0.5±1.2×10−4 subtract smoothly varying background Tim Gershon Flavour Physics 16 Signal confirmed in Υ(2S) transitions by BaBar, and by CLEO Why wasn't the ηb discovered at a hadronic experiment? ● Remember: Υ(1S) discovered at FNAL in 1977 – fixed target experiment: p on Be PRL 39 (1977) 252 ● ηb is lighter ● Hadron collisions produce all types of b hadrons ● So why couldn't the ηb be discovered, e.g., at the Tevatron? Tim Gershon Flavour Physics 17 Why wasn't the ηb discovered at a hadronic experiment? ● Remember: Υ(1S) discovered at FNAL in 1977 – fixed target experiment: p on Be PRL 39 (1977) 252 ● ηb is lighter ● Hadron collisions produce all types of b hadrons ● ● So why couldn't the ηb be discovered, e.g., at the Tevatron? It's all about the trigger! – need clean signature for trigger and reconstruction – CDF search used ηb →J/ψJ/ψ decay, with predicted BF ~ 0! Tim Gershon Flavour Physics CDF note 8448 18 Digression on a digression: The “Oops Leon” PRL 36 (1976) 1236 Homework exercise: 1. Read this paper 2. Do you find the “discovery” convincing? 3. Explain what's wrong Tim Gershon Flavour Physics 19 ATLAS arXiv:1112.5154 More new particles CMS arXiv:1204.5955 χb(3P) Tim Gershon Flavour Physics Ξb*0 20 The smoking gun exotic hadron: A charged charmonium-like state B0→Z(4430)–K+, Z(4430)–→ψ'π– Belle PRL 100 (2008) 142001 BABAR PRD 79 (2009) 112001 Clear peak Still there in more detailed analysis PRD 80 (2009) 031104 Data consistent with Kπ reflections Slight peak but no evidence for new state But also consistent with Belle Need more experimental input Tim Gershon Flavour Physics (CDF, D0, ATLAS, CMS or LHCb) 21 Charged bottomonium-like states Belle PRL 108 (2012) 122001 hb(1S)π+ Υ(1S)π+ hb(2S)π+ Υ(2S)π+ Υ(3S)π+ Tim Gershon Flavour Physics 22 OK, back to weak physics Tim Gershon Flavour Physics 23 Direct CP violation ● ● – Condition for DCPV: |A/A|≠1 – Need A and A to consist of (at least) two parts – ● with different weak (φ) and strong (δ) phases Often realised by “tree” and “penguin” diagrams A = ∣T ∣e ∣P∣e A = ∣T ∣e ∣P∣ e 2 ∣T∣∣P∣ sin T − P sin T − P ∣ A∣2−∣ A∣2 ACP = = ∣ A∣2∣ A∣2 ∣T∣2∣P∣2 2 ∣T∣∣ P∣cos T − P cos T − P i T −T i P −P i T T i P P Example: B→Kπ (weak phase difference is γ) Tim Gershon Flavour Physics 24 The famous penguin story Tim Gershon Heavy Flavour Physics 25 The famous penguin story Tim Gershon Flavour Physics 26 Direct CP asymmetries in charmless hadronic B decays Tim Gershon Flavour Physics 27 Direct CP violation in B→Kπ ● Direct CP violation in B→Kπ sensitive to γ too many hadronic parameters ⇒ need theory input NB. interesting deviation from naïve expectation Belle Nature 452 (2008) 332 ” A (K–π+) = –0.087 ± 0.008 e l CP zz u – 0 p A (K π ) = +0.037 ± 0.021 π CP “K HFAG averages Could be a sign of new physics … … first need to rule out possibility of larger than expected QCD corrections Tim Gershon Heavy Flavour Physics 28 Clean observables in B→Kπ (etc.) ● Measure more Bu,d→Kπ decays & relate by isospin ● Perform similar analysis on B→K*π &/or B→Kρ – ● Measure Bs→KK decays & relate by U-spin – ● Dalitz plot analyses of Kππ final states extract both amplitudes and relative phases → more observables e.g. relation between time-dependent CP violation observables in Bs→K+K– and B0→π+π– Dalitz plot analyses of Bs→KKπ Tim Gershon Flavour Physics Note: flavour symmetries very useful But, still get theory error from symmetry breaking (difficult to evaluate) … data driven methods will win in the end (unless miracle breakthrough) 29 + – B→h h' at hadron colliders Excellent channel to profit from displaced vertex trigger ● Particle ID extremely important LHCb arXiv:1202.6251 ● Tim Gershon Flavour Physics K+π– π+K– π+π– K+ K– CDF PRL 103 (2009) 031801 LHCb-CONF-2012-007 30 0 + – 0 + B → π π & Bs → K K First CP violation measurements in these channels at a hadron collider (B0 → π+π–) / ever (Bs0 → K+K–) 5359 ± 96 signal events Tim Gershon Flavour Physics – LHCb-CONF-2012-007 7155 ± 97 signal events 31 Importance of γ from B→DK ● γ plays a unique role in flavour physics the only CP violating parameter that can be measured through tree decays (*) (*) ● more-or-less A benchmark Standard Model reference point ● ∝ V cb V doubly important after New Physics is observed ∗ us Tim Gershon Flavour Physics ∝ V ub V ∗cs Variants use different B or D decays – require a final state common to both D0 and D0 32 Why is B→DK so nice? ● ● For theorists: – theoretically clean: no penguins; factorisation works – all parameters can be determined from data For experimentalists: – many different observables (different final states) – all parameters can be determined from data – γ & δB (weak & strong phase differences), rB (ratio of amplitudes) γ Tim Gershon Flavour Physics γ 33 B→DK methods ● Different D decay final states – – – – ● CP eigenstates, e.g. K+K– (GLW) doubly-Cabibbo-suppressed decays, e.g. K+π– (ADS) singly-Cabibbo-suppressed decays, e.g., K*+K– (GLS) self-conjugate multibody decays, e.g., KSπ+π– (GGSZ) Different B decays never studied before (or not much) – B–→DK–, D*K– , DK*– B0→DK*0 (or B→DKπ Dalitz plot analysis) B0→DKS, Bs0→Dφ (with or without time-dependence) – Bs0→DsK, B0→D(*)π (time-dependent) – – Tim Gershon Flavour Physics Search for direct CP violation caused by γ≠0 All parameters from data – no theory input needed 34 Evidence for direct CP violation (γ≠0) Latest results on B→DK : GLW Tim Gershon Flavour Physics LHCb arXiv:1203.3662 35 The other Unitarity Triangles ● High statistics available at LHCb will allow sensitivity to smaller CP violating effects – CP violating phase in Bs oscillations (O(λ4)) ● – CP violating phase in D0 oscillations (O(λ5)) ● ● Bs oscillations (Δms) measured 2006 (CDF) D0 oscillations (xD = ΔmD/ΓD & yD = 2ΔΓD/ΓD) measured 2007 (Babar, Belle, later CDF) Observations of CP violation in both K0 and B0 systems won Nobel prizes! Tim Gershon Flavour Physics 36 Time-dependent CP Violation Formalism ● Generic (but shown for Bs) decays to CP eigenstates Tim Gershon New Physics CP Violation Flavour&Physics 37 Time-dependent CP Violation Formalism ● Generic (but shown for Bs) decays to CP eigenstates CP violating asymmetries 2 A dir CP = C CP = Tim Gershon Flavour Physics 1−∣CP∣ 2 1∣CP∣ A = CP conserving parameter 2 ℜ CP 2 1∣CP∣ dir 2 CP A 2 mix CP = SCP = A A A mix 2 CP 2 ℑCP 2 1∣CP∣ =1 38 Time-dependent CP Violation Formalism ● ● Generic (but shown for Bs) decays to CP eigenstates Untagged analyses still sensitive to some interesting physics Tim Gershon New Physics CP Violation Flavour&Physics 39 Time-dependent CP Violation Formalism ● Generic (but shown for Bs) decays to CP eigenstates 0 0 0 ● In some channels, expect no direct CP violation ● and/or no CP violation in mixing Tim Gershon New Physics CP Violation Flavour&Physics 40 Time-dependent CP Violation Formalism ● Generic (but shown for Bs) decays to CP eigenstates 1 0 1 0 ● In some channels, expect no direct CP violation ● Bd case: ΔΓ negligible Tim Gershon New Physics CP Violation Flavour&Physics 41 Time-dependent CP Violation Formalism ● Generic (but shown for Bs) decays to CP eigenstates 1 1 yΓt xΓt 1 1 yΓt xΓt ● In some channels, expect no direct CP violation ● Bd case: ΔΓ negligible ● D0 case: both x = Δm/Γ and y=ΔΓ/2Γ small Tim Gershon New Physics CP Violation Flavour&Physics 42 Charm mixing and CP violation HFAG world average Including results from BABAR, Belle, CDF, CLEO(c), FOCUS Inconsistent with no mixing point (0,0) Tim Gershon Flavour Physics Consistent with no CP violation point (1,0) At LHCb can use D→K+K– to measure mix ● A y (untagged or tagged); A xD (tagged) ΔΓ D CP Many other possible channels 43 + – Evidence for CP violation in D → h h decays LHCb PRL 108 (2012) 111602 Measurement of CP asymmetry at pp collider requires knowledge of production and detection asymmetries; e.g. for D0→f, where D meson flavour is tagged by D*+→D0π+ decay final state detection asymmetry vanishes for CP eigenstate Cancel asymmetries by taking difference of raw asymmetries in two different final states (Since AD and AP depend on kinematics, must bin or reweight to ensure cancellation) D0→K+K– 1.4M events Tim Gershon Flavour Physics D0→π+π– 0.4M events 44 + – Evidence for CP violation in D → h h decays LHCb PRL 108 (2012) 111602 Result, based on 0.62/fb of 2011 data ΔACP = [−0.82 ± 0.21(stat.) ± 0.11(syst.)]% ΔACP related mainly to direct CP violation (contribution from indirect CPV suppressed by difference in mean decay time) Tim Gershon Flavour Physics 45 + – Evidence for CP violation in D → h h decays ● Naive SM expectation is for decays to be tree-dominated ● ● Penguin contributions are possible for singly-Cabibbosuppressed decays but CKM suppression is severe So CP violation effects should be O(10–4) … or should they? ● ● ● ● ● ● ● ● ● Implications of the LHCb Evidence for Charm CP Violation arXiv:1111.4987 Direct CP violation in two-body hadronic charmed meson decays arXiv:1201.0785 CP asymmetries in singly-Cabibbo-suppressed D decays to two pseudoscalar mesons arXiv:1201.2351 Direct CP violation in charm and flavor mixing beyond the SM arXiv:1201.6204 New Physics Models of Direct CP Violation in Charm Decays arXiv:1202.2866 Repercussions of Flavour Symmetry Breaking on CP Violation in D-Meson Decays arXiv:1202.3795 On the Universality of CP Violation in Delta F = 1 Processes arXiv:1202.5038 The Standard Model confronts CP violation in D0→π+π− and D0→K+K− arXiv:1203.3131 A consistent picture for large penguins in D → pi+pi-, K+K- arXiv:1203.6659 Tim Gershon Flavour Physics … and many others! Further experimental input needed to clarify whether CPV is SM or NP 46 Φs = –2βs (Bs→J/ψφ) ● VV final state three helicity amplitudes → mixture of CP-even and CP-odd disentangled using angular & time-dependent distributions → additional sensitivity many correlated variables → complicated analysis ● LHCb also uses Bs→J/ψf0 (f0→π+π–) – – CP eigenstate; simpler analysis fewer events; requires input from J/ψφ analysis (Γs, ΔΓs) Tim Gershon Flavour Physics 47 Bs→J/ψφ formalism ± signs differ for – Bs and Bs Tim Gershon Flavour Physics 48 CP violation in Bs → J/ψφ & J/ψππ LHCb-PAPER-2011-028 0.37/fb LHCb-CONF-2012-002 LHCb-PAPER-2012-005 LHCb-PAPER-2012-006 All 1/fb LHCb-CONF-2012-002 Tim Gershon Flavour Physics 49 CP violation in Bs → J/ψφ & J/ψππ Ambiguity resolution ●Tagged time-dependent angular analysis of J/ψφ with 1/fb ●Amplitude analysis to determine CP content of J/ψππ ●Tagged time-dependent analysis of J/ψππ ● Tim Gershon Flavour Physics LHCb-PAPER-2011-028 LHCb-CONF-2012-002 LHCb-PAPER-2012-005 LHCb-PAPER-2012-006 50 Rare Decays Tim Gershon Flavour Physics 51 b→sγ rate and photon energy spectrum Archetypal FCNC probe for new physics Belle PRL 103 (2009) 241801 B B X s E Tim Gershon B physics Flavourexperiments Physics −4 =3.45±0.15±0.40×10 1.7 GeV consistent with the SM prediction 52 b→sγ photon polarisation measurement ● Search for time-dependent asymmetry Observable effect requires NP: left-handed current & new CP phase ● Excellent prospects for LHCb with Bs→φγ LHCb arXiv:1202.6267 Tim Gershon B physics Flavourexperiments Physics + – 2 Can also use, eg., B→K*e e (low q ) 53 + – B→K*μ μ ● b→sl+l– processes also governed by FCNCs – ● rates and asymmetries of many exclusive processes sensitive to NP Queen among them is Bd→K*0μ+μ– – – – – superb laboratory for NP tests experimentally clean signature many kinematic variables … … with clean theoretical predictions (at least at low q2) Tim Gershon B physics Flavourexperiments Physics 54 Operator Product Expansion Build an effective theory for b physics – – – take the weak part of the SM integrate out the heavy fields (W,Z,t) (like a modern version of Fermi theory for weak interactions) Wilson coefficients ● encode information on the weak scale ● are calculable and known in the SM (at least to leading order) ● are affected by new physics For K*μμ we care about C7 (also affects b→sγ), C9 and C10 Tim Gershon B physics Flavourexperiments Physics 55 Effective operators Four-fermion operators (except Q7γ & Q8g) – dimension 6 Tim Gershon B physics Flavourexperiments Physics 56 + – Theory of B→K*μ μ ● Given for inclusive b→sμ+μ– for simplicity – ● physics of exclusive modes ≈ same but equations are more complicated (involving form factors, etc.) Differential decay distribution Tim Gershon B physics Flavourexperiments Physics This term gives a forwardbackward asymmetry 57 LHCb-CONF-2012-008 Tim Gershon Flavour Physics 58 LHCb-CONF-2012-008 ZOOM First measurement of the zero-crossing point of the forward-backward asymmetry q20 = (4.9+1.1−1.3) GeV2 (SM predictions in the range 4.0 – 4.3 GeV2) Tim Gershon 59 Flavour Physics + – Bs→μ μ Killer app. for new physics discovery ● Very small in the SM ● Huge NP enhancement (tan β = ratio of Higgs vevs) ● Clean experimental signature − SM BR B s Tim Gershon B physics Flavourexperiments Physics = 3.3±0.3×10 −8 − MSSM BR B s 6 4 ∝ tan / M A0 60 + – Latest results on Bs→μ μ ATLAS (2.4/fb) arXiv:1204.0735 CMS (5/fb) arXiv:1203.3976 ATLAS B(Bs→μ+μ–) < 2.2 (1.9) × 10−8 @ 95% (90%) CL CMS B(Bs→μ+μ–) < 7.7 (6.4) × 10−9 @ 95% (90%) CL Tim Gershon Flavour Physics 61 + – Latest results on Bs→μ μ LHCb (1/fb) arXiv:1203.4493 Standard Model expectation, e.g. (3.2 ± 0.2) x 10–9 Buras, arXiv:1012.1447 Tim Gershon Flavour Physics Why does LHCb get a better limit than ATLAS/CMS? 62 Implications G.Dissertori Moriond QCD summary talk: “Numbers most often mentioned: 3.2 x 10–9 and 125” … before ... Tim Gershon Flavour Physics N. Mahmoudi at Moriond 63 Implications G.Dissertori Moriond QCD summary talk: “Numbers most often mentioned: 3.2 x 10–9 and 125” “the wow plot” Simple TeV-scale models with large tan β ~ ruled out … after ... Tim Gershon Flavour Physics N. Mahmoudi at Moriond 64 LHCb upgrade ● To fully exploit LHC potential for heavy flavour physics will require an upgrade to LHCb – full readout & trigger at 40 MHz to enable high L running – “high L” = 1033/cm2/s (so independent of machine upgrade) – planned for 2018 shutdown Tim Gershon B physics Flavourexperiments Physics 65 What is the LHC era? Tim Gershon Flavour Physics Probably already out-of-date … it is the foreseeable future! 66 Other future flavour experiments ● SuperKEKB/Belle2 & SuperB – ● B→τν, inclusive measurements, τ physics, … Rare kaon decays K+→π+νν (NA62, CERN); K0→π0νν (K0T0, J-PARC) – – Muon to electron conversion (charged lepton flavour – ● violation) – COMET/PRIME (J-PARC); mu2e (FNAL) Tim Gershon B physics Flavourexperiments Physics 67 B→τν and charged Higgs limits ● Pure leptonic decays of charged B mesons very clean – clean SM prediction – clean effect of charged Higgs (2HDM or SUSY) BR B l SM = 2 2 l 2 B G F mB 2 m m l 1− 8 m 2 2 f B∣V ub∣ B BR B l NP = BR B l SM 1− 2 B 2 H m m 2 2 tan Belle PRD 82 (2010) 071101 Tim Gershon B physics Flavourexperiments Physics 68 The holy grail of kaon physics: K→πνν Next generation experiments should measure these decays for the 1st time ● Tim Gershon Flavour Physics ● ● K+→π+νν (NA62, CERN) K0→π0νν (K0T0, J-PARC) Proposals also at FNAL 69 Future projects nuclear transitions PIBETA KLOE-2, NA62, KOTO pion decays NA48, KTeV, KLOE, ISTRA kaons hyperon decays Project X CHORUS hadronic matrix elements tau decays neutrino interactions chiral perturbation theory KEDR, FOCUS, CLEO, BES charm τ-charm factory dispersion relations lattice QCD flavour symmetries BABAR, BELLE, LHCb bottom great progress in theory heavy quark effective theories anticipated Belle-2, SuperB, ALEPH, DELPHI, L3, OPAL LHCb upgrade W decays operator product expansion Tim Gershon Flavour Physics CDF, D0, ATLAS, CMS top perturbative QCD 70 Summary ● ● ● We still don't know: – why there are so many fermions in the SM – what causes the baryon asymmetry of the Universe – where exactly the new physics is … – … and what it's flavour structure is Prospects are good for progress in the next few years We need a continuing programme of flavour physics into the 2020s – complementary to the high-pT programme of the LHC Tim Gershon B physics Flavourexperiments Physics 71 References and background reading ● Reviews by the Particle Data Group – ● Heavy Flavour Averaging Group (HFAG) – ● http://ckmfitter.in2p3.fr/ & http://www.utfit.org/ Review journals (e.g. Ann. Rev. Nucl. Part. Phys.) – ● http://www.slac.stanford.edu/xorg/hfag/ CKMfitter & UTfit – ● http://pdg.lbl.gov/ http://nucl.annualreviews.org Proceedings of CKM workshops – ● Phys.Rept. 494 (2010) 197, eConf C100906 Books – – CP violation, I.I.Bigi and A.I.Sanda (CUP) CP violation, G.C.Branco, L.Lavoura & J.P.Silva (OUP) Tim Gershon Flavour Physics Back up b hadron spectroscopy – Observation of the Ωb CDF PRD 80 (2009) 72003 4.2/fb Ξb– D0 PRL 101 (2008) 232002 m(Ωb) = 6054.4 ± 6.8 (stat.) ± 0.9 (syst.) MeV 6165 ± 10 (stat) ± 13(syst.) MeV significant discrepancy to be understood Ωb– Tim Gershon Flavour Physics Ωb– 74 b hadron spectroscopy – Observation of the Σb CDF PRL 99 (2007) 202001 Fully hadronic decay chain: Σb(*) ±→Λb0π± Λb0→Λc+π– Λc+→pK–π+ Impressive demonstration of B physics potential with hadronic triggers Tim Gershon Flavour Physics 75 More b hadron spectroscopy Study of the quantum numbers of X(3872) Discovery of the Y(4140) in B→J/ψφK PRL 98 (2007) 132002 CDF Note 10244 & PRL 102 (2009) 242002 Tim Gershon Flavour Physics 76 Latest results on B→DK : GGSZ BABAR arXiv:1005.1096 γ = (68 +15−14 ± 4 ± 3)° BELLE PRD 81 (2010) 112002 Φ3 = (78 +11−12 ± 4 ± 9)° Evidence for direct CP violation (γ≠0) Uncertainty due to assumed D→KSπ+π– decay model Tim Gershon Flavour Physics 77 Model independent B→DK Dalitz measurements ● – Use CP-tagged CLEOc data to measure average D0–D0 phase difference A.Powell at Beauty 2009 Tim Gershon Flavour Physics 78